Not only does this free up key system resources, it also eliminates traces of your browsing activity to protect your privacy.
Iolo System Mechanic removes junk files and unwanted apps, blocks bloatware and unwanted auto-run settings, clears out RAM and wipes various logs, browser histories and caches. This is a very large extra charge, so make sure to double-check before entering your payment details.
Update: A recent change to Iolo's checkout process means you will be automatically subscribed to a $19.99 (about £15 / AU$25) per month support package when you purchase a product.